Cobalt-Catalyzed Alkylation of Secondary Alcohols with Primary Alcohols via Borrowing Hydrogen/Hydrogen Autotransfer

Article abstract of DOI:10.1002/chem.201701211

Alcohols are promising sustainable starting materials because they can be obtained from abundant and indigestible biomass. The substitution of expensive noble metals in catalysis by earth abundant 3d metals, such as Mn, Fe, or Co, (nonprecious or base metals) is a related key concept with respect to sustainability. Here, we report on the first cobalt-catalyzed alkylation of secondary alcohols with primary alcohols. Easy-to-synthesize and easy-to-activate PN₅P-pincer-ligand-stabilized Co complexes developed in our laboratory mediate the reaction most efficiently. The catalysis is applicable to a broad substrate scope and proceeds under relatively mild conditions. We have even demonstrated the coupling of a variety of purely aliphatic alcohols with a base or nonprecious metal catalyst. Mechanistic studies indicate that the reaction follows the borrowing hydrogen or hydrogen autotransfer concept.

Full text of DOI:10.1002/chem.201701211

A Journal of
Accepted Article
Title: Cobalt-Catalyzed Alkylation of Secondary Alcohols with Primary
Alcohols via Borrowing Hydrogen/Hydrogen Autotransfer
Authors: Rhett Kempe, Frederik Freitag, and Torsten Irrgang
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To be cited as: Chem. Eur. J. 10.1002/chem.201701211
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Cobalt-Catalyzed Alkylation of Secondary Alcohols with Primary
Alcohols via Borrowing Hydrogen/Hydrogen Autotransfer
Frederik Freitag,[a] Torsten Irrgang,[a] and Rhett Kempe*[a]
Alcohols are promising sustainable starting materials since they can
be obtained from abundant and indigestible biomass. The substitution
of expensive noble metals in catalysis by earth abundant 3d metals,
such as Mn, Fe or Co, (nonprecious or base metals) is a related key
concept with respect to sustainability. Herein, we report on the first
cobalt-catalyzed alkylation of secondary alcohols with primary
alcohols. Easy-to-synthesize and easy-to-activate PN5P-pincer ligand
stabilized Co complexes developed in our laboratory mediate the
reaction most efficiently. The catalysis is applicable to a broad
substrate scope and proceeds under relatively mild conditions. We
have even demonstrated the coupling of a variety of purely aliphatic
alcohols with a base or nonprecious metal catalyst. Mechanistic
studies indicate that the reaction follows the borrowing hydrogen or
hydrogen autotransfer concept.
aromatic, as well as purely aliphatic alcohols remains unknown.
Herein, we report on the first cobalt-catalyzed version of the
hetero-alkylation of alcohols by alcohols following the BH/HA
concept. The catalyst is able to couple substituted
1-phenylethanol derivatives with primary aromatic or aliphatic
alcohols as well as secondary aliphatic alcohols with primary
aromatic or aliphatic alcohols. Triazine-based PN5P pincer ligand
complexes developed in our laboratory are most efficient in these
reactions. They are easily and nearly quantitatively obtainable in
two steps from commercially available and inexpensive starting
materials. In addition, the precatalysts self-activate under basic
conditions.[11, 15, 21] The related pyridine-based PN3P pincer ligand
class was introduced by Haupt and coworkers[22, 23] and has
intensively been studied by the Kirchner group[24]
.
The borrowing hydrogen/hydrogen autotransfer methodology
(BH/HA) is a prominent example of an alcohol re-functionalization
concept.[1, 2] The alcohol is dehydrogenated to a carbonyl
compound, followed by a reaction with a nucleophile and
subsequent reduction with the “borrowed” hydrogen. Because of
dwindling crude oil reserves and growing public awareness for the
consequences of climate change, the search for alternative
carbon resources is getting increasingly urgent.[3, 4] In this regard,
alcohols are promising as starting materials due to the possibility
of obtaining them from abundantly available, indigestible and
barely used biomass (lignocellulose).[5-7] The direct hetero-
coupling of two alcohols follows the BH/HA concept and
exclusively uses alcohols as starting materials. This reaction has
been reported to proceed employing a multitude of noble metal
catalysts.[8] However, noble metals are rare and their
conservation is a key issue with regard to a sustainable future.
One possible approach is the replacement of precious metals in
key technologies by more abundant metals. Beside Mn[9], and
Fe[10], especially Co complexes[11-17] have been disclosed as
highly active and selective catalysts for a variety of reactions
following the BH/HA mechanism (see Scheme 1). Iron-[18] and
nickel-based[19] homogenous catalysts have been described for
the alkylation of secondary alcohols by primary alcohols.[20]
Unfortunately, the substrate scope is limited, especially for the
nickel catalyzed version. A broadly applicable catalyst system
based on a nonprecious metal, which is capable of coupling
Scheme 1. Cobalt-Catalyzed C-C- and C-N-Coupling Reactions based on
BH/HA.
The coupling of 1-phenylethanol (1a) and benzyl alcohol (2a) to
3a was chosen as a model reaction (Table 1, top). Common
reaction parameters were optimized starting with precatalyst 4a
[a]
F. Freitag, Dr. T. Irrgang, Prof. Dr. R. Kempe
Anorganische Chemie II—Katalysatordesign
Universität Bayreuth
(for further details see SI). Eight different cobalt-based PN3-5
P
complexes and CoCl2 were tested (Table 1), in order to find the
most suitable precatalyst for the model reaction. All reactions
using precatalysts with pyridine backbone (Table 1, 5a-c,
entries 6-8) yielded no product. These results could be explained
by the low hydrogenation activity of the pyridine-based
95540 Bayreuth (Germany)
E-mail: kempe@uni-bayreuth.de
Supporting information for this article is given via a link at the end of
the document.((Please delete this text if not appropriate))
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complexes.[21] Hydrogenation/reduction is a key step in BH/HA
reactions. When CoCl2 (Table 1, entry 9) was used, 3a was
obtained in only 2 % yield. In contrast, the triazine-based
complexes (Table 1, 4a-e, entries 1-5) were much more active.
The yield of 3a improved to 25 % (Table 1, entry 3) with 4c as the
best precatalyst.
were varied and used in combination with 1-phenylethanol (1a),
giving rise to products with methyl group in ortho-, meta- and
para-position of the phenyl ring (Table 2, entries 7-9) in yields of
isolated 73-79 %. The electron-rich 2- and 4-methoxybenzyl
alcohols (Table 2, entries 10, 11) gave the corresponding
products in 69 (3j) and 77 % (3k). However, the reaction time had
to be prolonged to 44 h for the ortho substituted reactant (Table 2,
entry 10). This might be due to the methoxy substituent being
much closer to the hydroxyl group and thus causing steric
hindrance.
Table 1. Precatalyst Screening.[a]
Table 2. Substrate Scope of Aromatic Alcohols (1 and 2).[a]
Entry
Precatalyst
Yield [%][b]
1
2
3
4
5
6
7
8
9
4a: R1 = Ph; R2 = iPr
4b: R1 = NH-C3H5; R2 = iPr
4c: R1 = 4-F3C-C6H4; R2 = iPr
4d: R1 = Me; R2 = iPr
4e: R1 = Me; R2 = Cy
5a: R1 = H; R2 = iPr
5b: R1 = Me; R2 = iPr
5c: R1 = H; R2 = Ph
CoCl2
12
24
Yield
Entry
Product (3a-n)
R1
R2
25 (90[c]
16
)
[%][b]
1
2
3
4
5
C6H5
H
H
H
H
H
76
3a
3b
3c
3d
3e
23
4-OMe-C6H4
4-Me-C6H4
4-Cl-C6H4
3-Cl-C6H4
80
0 (3[c]
0 (5[c]
0 (1[c]
2
)
)
)
77
79
61
6
3f
C4H3S
H
44
[a]
1a
(1.5 mmol),
2a
(1.0 mmol),
KHMDS
(potassium
bis(trimethylsilyl)amide, 1.1 mmol), 2 mol% (20 µmol) precatalyst, toluene
(2 mL), 80 °C (oil bath), 20 h, closed system. [b] Determined via GC
analysis. [c] Yields determined via GC for the alkylation under optimized
reaction conditions: 1a (1.5 mmol), 2a (1.0 mmol), KHMDS (1.1 mmol),
5 mol% (50 µmol) precatalyst, toluene (2 mL), 110 °C (oil bath), 20 h,
closed system.
7
3g
3h
3i
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
2-Me
3-Me
4-Me
2-MeO
4-MeO
4-Cl
74
73
79
69
77
60
49
64
8
9
10[c]
11
12
13
14[d]
3j
The conversion of 2a was quantitative and the yield of 3a could
be increased to 90 % by further optimization of the reaction
conditions regarding temperature and catalyst loading. In
summary, the reaction proceeded best in toluene, with 1.1 eq.
KHMDS, a reactant 1/2 ratio of 1.5:1.0 and precatalyst 4c
(5 mol%) at 110 °C for 20 h.
3k
3l
3m
3n
4-Br
3,4-
Next, the substrate scope for the alkylating system was
investigated under these conditions. It seemed most reasonable
to us to start with reactants derivable from the aromatic model
substrates 1a and 2a, from which 3a had been isolated in 76 % of
yield. At first, aromatic secondary alcohols 1 with different
substitution patterns were reacted with benzyl alcohol (2a).
Methoxy-, methyl- and chloro- (Table 2, entries 2-4)
functionalities were introduced in para position of 1 with nearly
identical isolated yields. m-Chloro-1-phenylethanol (Table 2,
entry 5) gave the corresponding product in a slightly lower yield of
61 %. Even a reactant with a potentially catalyst-inhibiting
thiophene motif (Table 2, entry 6) gave 3f in an acceptable 44 %
yield. After that, primary alcohols derived from benzyl alcohol
(CH)4
[a] 1 (1.5 mmol), 2 (1.0 mmol), KHMDS (1.1 mmol), 5 mol% 4c (50 µmol),
toluene (2 mL), 110 °C (oil bath), 20 h, closed system. [b] Yields of isolated
products. [c] Reaction time: 44 h. [d] 130 °C (oil bath).
p-Chloro- and p-bromobenzyl alcohol (Table 2, entries 12, 13)
were converted into products 3l (60 %) and 3m (49 %), in order
to prove tolerance of the catalytic system for halides. The lower
yield of 3m is due to dehalogenation. Next, we investigated the
reaction of aliphatic primary alcohols with aromatic secondary
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alcohols. Therefor 1a was alkylated with the two unbranched
alcohols 1-hexanol (Table 3, entry 1) and 1-octanol (Table 3,
entry 2), which delivered the products in nearly identical yields of
49 (3o) and 51 % (3p). Cyclopropylmethanol was employed as a
branched example of an aliphatic reactant, giving the
corresponding product 3q in a slightly higher 63 % yield.
4-Methoxyphenylethanol was also tested in combination with
1-hexanol (Table 3, entry 4) and 1-octanol (Table 3, entry 5), in
order to show that these findings are not restricted to
1-phenylethanol (1a). Thus, products 3r and 3s were obtained in
a 46 and a 49 % isolated yield.
respectively. Consequently, the yields seem to decrease slightly
towards smaller carbon chains of the secondary alcohols.
After having shown the substrate scope especially for aliphatic
alcohols, further investigations were conducted gaining insight
into the mechanism of the catalysis. A time-conversion-plot
revealed that the alkylation between the model substrates 1a and
2a had finished after about 10 h.
Table 4. Coupling of aliphatic secondary alcohols (1) with primary alcohols
(2).[a]
Table 3. Reaction of aromatic secondary alcohols (1) and aliphatic primary
alcohols (2).[a]
Yield
[%][b]
Entry
Product (3t-aa)
R1
R2
1
2
3
cyclopropyl
cyclopropyl
cyclopropyl
C6H5
72
3t
Yield
[%][b]
3u
3v
n-heptyl
cyclohexyl
62
Entry
Product (3o-s)
R1
R2
54
1
2
3
H
H
H
n-pentyl
49
3o
3p
3q
4
5
3w
3x
n-hexyl
n-hexyl
(CH2)3C6H5
40
50
n-heptyl
51
n-heptyl
cyclopropyl
63
4
5
3r
OMe
OMe
n-pentyl
n-heptyl
46
49
6
7
8
3y
n-hexyl
(n = 5)
cyclohexyl
cyclohexyl
cyclohexyl
70
66
59
3s
3z
n-butyl
(n = 3)
3aa
n-propyl
(n = 2)
[a] 1 (1.5 mmol), 2 (1.0 mmol), KHMDS (1.1 mmol), 5 mol% 4c (50 µmol),
toluene (2 mL), 110 °C (oil bath), 20 h, closed system. [b] Yields of isolated
products.
[a] 1 (1.5 mmol), 2 (1.0 mmol), KHMDS (1.1 mmol), 5 mol% 4c (50 µmol),
toluene (2 mL), 110 °C (oil bath), 20 h, closed system. [b] Yields of isolated
products.
Since the incorporation of primary aliphatic alcohols was possible,
we investigated the substrate scope for aliphatic secondary
alcohols. Consequently, 1-cyclopropylethanol, as a branched
aliphatic substrate, was applied along with benzyl alcohol
(Table 4, entry 1), delivering product 3t in 72 % yield.
Furthermore, 1-octanol (Table 4, entry 2) as an unbranched, and
cyclohexanemethanol (Table 4, entry 3) as a branched alcohol,
were coupled with 1-cyclopropylethanol into 3u (62 %) and 3v
(54 %). Linear secondary alcohols were also successfully
deployed in the reaction. 2-Octanol was alkylated with 3-
phenylpropanol (Table 4, entry 4) in a 40 %, with 1-octanol
(Table 4, entry 5) in a 50 % and with cyclohexanemethanol
(Table 4, entry 6) even in a 70 % yield. Because of the rather high
yield of the latter, it seemed to be a suitable substrate for
examining how the length of the carbon chain influences the
alkylation. Thus, 2-hexanol (Table 4, entry 7) and 2-pentanol
(Table 4, entry 8) were coupled with cyclohexanemethanol and
the products were isolated in a 66 (3z) and a 59 % (3aa) yield,
The oxidation of starting materials 1a and 2a, as a key step of
the BH/HA mechanism, was investigated separately, in an
open system each. The depletion of the reactants, as well as
the produced compounds, imply that the oxidation of alcohols
is possible with the herein reported cobalt catalyst. As a
second key step, the postulated intermediates (chalcone, its
corresponding ketone, and the unsaturated alcohol) were
reduced to 3a. The usage of hydrogen and precatalyst 4c
resulted in 17, 84 and 80 % yields, respectively. Other
experiments demonstrated that the equilibrium of the alkylation
tends strongly to the alkylated products, since no back reaction
is observed. The investigations indicate that the reaction
proceeds via the BH/HA mechanism (see SI for further details).
We have reported the first cobalt-catalyzed version of the
alkylation of secondary alcohols with primary alcohols. We
used PN5P-pincer ligand complexes of cobalt, developed in our
laboratory and demonstrated that they are highly active in this
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Angew. Chem. 2016, 128, 11984–11988; h) M. Mastalir, M. Glatz, N.
Gorgas, B. Stöger, E. Pittenauer, G. Allmaier, L. F. Veiros, K. Kirchner,
Chem. Eur. J. 2016, 22, 12316–12320; i) A. Mukherjee, A. Nerush, G.
Leitus, L. J. Shimon, Y. Ben-David, N. A. Espinosa-Jalapa, D. Milstein, J.
Am. Chem. Soc. 2016, 138, 4298–4301; j) M. Perez, S. Elangovan, A.
Spannenberg, K. Junge, M. Beller, ChemSusChem 2017, 10, 83-86.
[10] For selected reviews see: a) T. Zell, D. Milstein, Acc. Chem. Res. 2015,
48, 1979–1994; b) I. Bauer, H.-J. Knölker, Chem. Rev. 2015, 115, 3170–
3387.
reaction. The catalysts are easy to synthesize from
inexpensive starting materials. The catalyst system we have
developed is applicable to a broad substrate scope. Even the
hetero-coupling of different aliphatic alcohols was
demonstrated.
[11] S. Rösler, M. Ertl, T. Irrgang, R. Kempe, Angew. Chem. Int. Ed. 2015, 54,
15046–15050; Angew. Chem. 2015, 127, 15260–15264.
[12] G. Zhang, Z. Yin, S. Zheng, Org. Lett. 2016, 18, 300–303.
[13] M. Mastalir, G. Tomsu, E. Pittenauer, G. Allmaier, K. Kirchner, Org. Lett.
2016, 18, 3462-3465.
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft for financial
support (KE 576/29-1) and Dr. Ulrike Lacher for HRMS
measurements.
[14] Z. Yin, H. Zeng, J. Wu, S. Zheng, G. Zhang, ACS Catal. 2016, 6, 6546–
6550.
[15] N. Deibl, R. Kempe, J. Am. Chem. Soc. 2016, 138, 10786–10789.
[16] G. Zhang, J. Wu, H. Zeng, S. Zhang, Z. Yin, S. Zheng, Org. Lett. 2017,
DOI: 10.1021/acs.orglett.7b00106.
Keywords: Alcohol • Alkylation • Borrowing Hydrogen/Hydrogen
Autotransfer • Cobalt • PNP ligands
[17] First cobalt-catalyzed reaction of alcohols with amines to form imines: G.
Zhang, S. K. Hanson, Org. Lett. 2013, 3, 650-653.
[1]
For selected reviews see: a) F. Huang, Z. Liu, Z. Yu, Angew. Chem. Int.
Ed. 2016, 55, 862–875; Angew. Chem. 2016, 128, 872-885; b) Y. Obora,
ACS Catal. 2014, 4, 3972–3981; c) C. Gunanathan, D. Milstein, Science
2013, 341, 1229712; d) Y. Obora, Y. Ishii, Synlett 2011, 1, 30–51; e) T.
Suzuki, Chem. Rev. 2011, 111, 1825–1845; f) G. E. Dobereiner, R. H.
Crabtree, Chem. Rev. 2010, 110, 681–703; g) T. D. Nixon, M. K.
Whittlesey, J. M. J. Williams, Dalton Trans. 2009, 753–762; h) M. H. S.
A. Hamid, P. A. Slatford, J. M. J. Williams, Adv. Synth. Catal. 2007, 349,
1555–1575; i) G. Guillena, D. J. Ramon, M. Yus, Angew. Chem. Int. Ed.
2007, 46, 2358–2364; Angew. Chem. 2007, 119, 2410-2416.
A. Quintard, J. Rodriguez, ChemSusChem 2016, 9, 28–30.
[18] J. Yang, X. Liu, D.-L. Meng, H.-Y. Chen, Z.-H. Zong, T.-T. Feng, K. Sun,
Adv. Synth. Catal. 2012, 354, 328–334.
[19] G. Tang, C.-H. Cheng, Adv. Synth. Catal. 2011, 353, 1918–1922.
[20] For transition metal free versions see: a) Q. Xu, J. Chen, Q. Liu, Adv.
Synth. Catal. 2013, 355, 697–704 (drastic conditions for aliphatic
substrates: 160 °C, 72 h, up to 30 mol% of the corresponding aldehyde;
no coupling of two aliphatic alcohols possible); b) L. J. Allen, R. H.
Crabtree, Green Chem. 2010, 12, 1362-1364 (mainly restricted to few
aromatic compounds).
[2]
[3]
[4]
[21] S. Rösler, J. Obenauf, R. Kempe, J. Am. Chem. Soc. 2015, 137, 7998–
8001.
M. Poliakoff, P. Anastas, Nature 2001, 413, 257.
M. Poliakoff, J. M. Fitzpatrick, T. R. Farren, P. T. Anastas, Science 2002,
297, 807–810.
[22] W. Schirmer, U. Flörke, H. Haupt, Z. Anorg. Allg. Chem. 1987, 545, 83–
97.
[5]
[6]
C. O. Tuck, E. Pérez, I. T. Horváth, R. A. Sheldon, M. Poliakoff, Science
2012, 337, 695–699.
[23] H. Li, B. Zheng, K.-W. Huang, Coord. Chem. Rev. 2015, 293-294, 116–
138.
T. P. Vispute, H. Zhang, A. Sanna, R. Xiao, G. W. Huber, Science 2010,
330, 1222–1227.
[24] Selected examples: a) F. Bertini, N. Gorgas, B. Stöger, M. Peruzzini, L.
F. Veiros, K. Kirchner, L. Gonsalvi, ACS Catal. 2016, 6, 2889–2893; b)
N. Gorgas, B. Stöger, L. F. Veiros, K. Kirchner, ACS Catal. 2016, 6,
2664–2672; c) S. Murugesan, B. Stöger, E. Pittenauer, G. Allmaier, L. F.
Veiros, K. Kirchner, Angew. Chem. Int. Ed. 2016, 55, 3045–3048; Angew.
Chem. 2016, 128, 3097-3100; d) S. R. M. M. de Aguiar, B. Stöger, E.
Pittenauer, M. Puchberger, G. Allmaier, L. F. Veiros, K. Kirchner, J.
Organomet. Chem. 2014, 760, 74–83; e) N. Gorgas, B. Stöger, L. F.
Veiros, E. Pittenauer, G. Allmaier, K. Kirchner, Organometallics 2014, 33,
6905–6914; f) S. Murugesan, B. Stöger, M. D. Carvalho, L. P. Ferreira,
E. Pittenauer, G. Allmaier, L. F. Veiros, K. Kirchner, Organometallics
2014, 33, 6132–6140.
[7]
[8]
D. M. Alonso, J. Q. Bond, J. A. Dumesic, Green Chem. 2010, 12, 1493.
Selected examples: a) Q. Wang, K. Wu, Z. Yu, Organometallics 2016,
35, 1251–1256; b) B. C. Roy, K. Chakrabarti, S. Shee, S. Paul, S. Kundu,
Chem. Eur. J. 2016, 22, 18147–18155; c) K. Chakrabarti, B. Paul, M.
Maji, B. C. Roy, S. Shee, S. Kundu, Org. Biomol. Chem. 2016, 14,
10988–10997; d) S. Ruiz-Botella, E. Peris, Chem. Eur. J. 2015, 21,
15263–15271; e) M. V. Jiménez, J. Fernández-Tornos, F. J. Modrego, J.
J. Pérez-Torrente, L. A. Oro, Chem. Eur. J. 2015, 21, 17877–17889; f)
W. Bai, G. Jia, Inorg. Chim. Acta 2015, 431, 234–241; g) P.
Satyanarayana, G. M. Reddy, H. Maheswaran, M. L. Kantam, Adv. Synth.
Catal. 2013, 355, 1859–1867; h) S. Liao, K. Yu, Q. Li, H. Tian, Z. Zhang,
X. Yu, Q. Xu, Org. Biomol. Chem. 2012, 10, 2973; i) T. Miura, O. Kose,
F. Li, S. Kai, S. Saito, Chem. Eur. J. 2011, 17, 11146–11151; j) K.-i. Fujita,
C. Asai, T. Yamaguchi, F. Hanasaka, R. Yamaguchi, Org. Lett. 2005, 7,
4017–4019.
[9]
For selected examples see: a) N. Deibl, R. Kempe, Angew. Chem. Int.
Ed. 2017, 56, 1663-1666; Angew. Chem. 2017, 129, 1685-1688; b) M.
Mastalir, M. Glatz, E. Pittenauer, G. Allmaier, K. Kirchner, J. Am. Chem.
Soc. 2016, 138, 15543-15546; c) S. Elangovan, M. Garbe, H. Jiao, A.
Spannenberg, K. Junge, M. Beller, Angew. Chem. Int. Ed. 2016, 55,
15364–15368; Angew. Chem. 2016, 128, 15590–15594; d) S. Elangovan,
J. Neumann, J.-B. Sortais, K. Junge, C. Darcel, M. Beller, Nat. Commun.
2016, 7, 12641; e) S. Elangovan, C. Topf, S. Fischer, H. Jiao, A.
Spannenberg, W. Baumann, R. Ludwig, K. Junge, M. Beller, J. Am.
Chem. Soc. 2016, 138, 8809–8814; f) N. A. Espinosa-Jalapa, A. Nerush,
L. J. Shimon, G. Leitus, L. Avram, Y. Ben-David, D. Milstein, Chem. Eur.
J. 2016, DOI: 10.1002/chem.201604991; g) F. Kallmeier, T. Irrgang, T.
Dietel, R. Kempe, Angew. Chem. Int. Ed. 2016, 55, 11806–11809;
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Entry for the Table of Contents (Please choose one layout)
Layout 2:
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Frederik Freitag, Torsten Irrgang, Rhett
Kempe*
Page No. – Page No.
Cobalt-Catalyzed Alkylation of
Secondary Alcohols with Primary
Alcohols via Borrowing
It is all about the al[Co]hol. – The first cobalt catalyst for the alkylation of secondary
alcohols with primary alcohols is reported. The system requires mild conditions with
a high substrate scope even for aliphatic motifs and yields of the isolated products
of up to 80 %.
Hydrogen/Hydrogen Autotransfer
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